Fire extinguishing system

ABSTRACT

A fire extinguishing system including a fluid source, at least one sprinkler ( 2 ), and distribution pipes ( 3 ). The distribution pipes ( 3 ) are formed at least partially as soft-steel metal pipe having a friction loss defined according to the Hazen-Williams formula (1), with P=6.05·10 5 ·L·Q 1.85 ·C (−1.85) ·d (−4.87) , in which P=pressure drop in the pipeline, in bar, Q=flow rate through the pipeline, in l/min, d=average inside diameter of the pipe, in mm, C=constant for the type and condition of the pipeline, and L=equivalent length of pipe sections and pipe fittings, in m. The distribution pipes ( 3 ) have an anti-corrosion coating on the inside in order to ensure a value for C in a range of 125 to 150 during commissioning of the fire extinguishing system.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/376,347 filed Aug. 1, 2014, which is National Stage of InternationalApplication No. PCT/EP2013/051394, filed Jan. 25, 2013, which claimspriority to European Application No. 12153964.7, filed Feb. 5, 2012. Theentire disclosures of the above applications are incorporated herein byreference.

FIELD

The present invention concerns a fire extinguishing system fordistributing an extinguishing medium, wherein such a fire extinguishingsystem at least comprises: means (1) for providing the extinguishingmedium, at least one means (2) for applying the extinguishing medium,transport means (3) for connecting the means (1) for providing theextinguishing medium to the at least one means (2) for applying theextinguishing medium.

In that case in accordance with the known state of the art the transportmeans (3) are at least partially in the form of mild steel metal pipe.

In that case the pipe friction loss in pipes is defined in accordancewith the Hazen-Williams formula (1) withP=6.05·10⁵ ·L·Q ^(1.85) ·C ^((−1.85)) ·d ^((−4.87))

wherein:

P=pressure drop in the pipe, in bars,

Q=through-flow rate through the pipe, in l/min,

d=mean inside diameter of the pipe, in mm,

C=constant for type and condition of the pipe, and

L=equivalent length of pipe and shaped portions, in m.

In principle the calculation of pressure drops in pipes on apredetermined pipe length is possible in particular using theDarcy-Weisbach equation which admittedly however is generally extremelycomplicated to use. For that reason the use of the empiricalHazen-Williams formula (1) has gained acceptance generally and inparticular for the design and calculation of sprinkler installations.

In principle the calculation of pressure drops in pipes on apredetermined pipe length is possible in particular using theDarcy-Weisbach equation which admittedly however is generally extremelycomplicated to use. For that reason the use of the empiricalHazen-Williams formula (1) has gained acceptance generally and inparticular for the design and calculation of sprinkler installations.

BACKGROUND AND SUMMARY

The inventors initially found themselves confronted with the task of amonetary improvement in the design and operation of sprinklerinstallations. Particularly the aspect of the task of monetaryimprovement in the operation of sprinkler installations involves therecognized problem that, in sprinkler installations, after many monthsafter having been brought into operation, leakages in the couplings asthe typical connections of transport means (3) in the form of metalpipes can sometimes occur, which ultimately leads to repair operationsand insurance damage and thus a significant increase in costs withinoperation of sprinkler installations. Admittedly the last-mentionedproblem can be overcome by galvanized metal pipes in fitments, but asolution which is satisfactory in all respects and which in particularcan also be financially viable above all for larger sprinklerinstallations has however still to be achieved in spite of numerousapproaches, especially as it is precisely that galvanized pipes are tobe assessed from a rather critical point of view in regard tooperational problems.

The inventors tried in their considerations to also use the mathematicaldependencies of values in the Hazen-Williams formula (1). Therein inparticular a relationship between the pressure drop in the pipe, P[bar],and the dimension-less constant C is of interest. In accordance with theinformation in the German Standard DIN EN 12845, Version 07/2009, inthat respect the values of following Table 1 apply:

TABLE 1 Type of pipe C-value Cast iron 100 Ductile cast iron 110 Steel,black - this corresponds to mild steel in accordance with 120 thepresent invention Galvanized steel 120 Centrifugal concrete 130Cement-clad cast iron 130 Non-rusting steel - this is high-quality steel140 Copper 140 Reinforced glass fiber 140

The inventors finally realized that both aspects of the underlyingproblem can be solved by means of a fire extinguishing system fordistributing an extinguishing medium, wherein such a fire extinguishingsystem has at least: means (1) for providing the extinguishing medium,at least one means (2) for applying the extinguishing medium, transportmeans (3) for connecting the means (1) for providing the extinguishingmedium to the at least one means (2) for applying the extinguishingmedium, wherein the transport means (3) are at least partially in theform of mild steel metal pipe, wherein the pipe friction loss in pipesis defined in accordance with the Hazen-Williams formula (1) withP=6.05·10⁵ ·L·Q ^(1.85) ·C ^((−1.85)) ·d ^((−4.87))

wherein:

P=pressure drop in the pipe, in bars,

Q=through-flow rate through the pipe, in l/min,

d=mean inside diameter of the pipe, in mm,

C=constant for type and condition of the pipe, and

L=equivalent length of pipe and shaped portions, in m.

The fire extinguishing system proposed here is characterized in that:the transport means (3) which are at least partially in the form of mildsteel metal pipe have an at least inwardly disposed corrosion protectioncoating, and the inwardly disposed corrosion protection coating isadapted to ensure a value for C in a range of 125 to 150 when the fireextinguishing system is commissioned.

The value C in that respect refers to the transport means (3) which arein the form of a mild steel metal pipe and which have the inwardlydisposed corrosion protection coating characterizing the invention.

According to the inventors' realization which is essential to theinvention an inwardly disposed corrosion protection coating for thetransport means (3) which at least partly are in the form of a mildsteel metal pipe is singly and solely suitable for ensuring for theconstant C a value in a range of 125 to 150 when the fire extinguishingsystem is commissioned and—preferably—equally also within a period ofuse of a year and quite particularly preferably also within a period ofuse of five years after commissioning of the fire extinguishing system.Ensuring a value for C in the range characterizing the invention andstill further in the preferred ranges of the invention presented here,on the basis of the inwardly disposed corrosion protection coating whichis provided in that way, affords a completely even and non-poroussealing means in respect of the insides of the metal pipes (3), which nolonger has the extinguishing medium which is passed through the metalpipes (3) infiltrating therebeneath, even over many years, and thatapplies even for the ends of the metal pipes (3), which are broughttogether in the couplings.

Quite particularly preferably the inwardly disposed corrosion protectioncoating for the transport means (3) which at least partly are in theform of a mild steel metal pipe is suitable, for the constant C, forensuring a value in a range of 135 to 150 when the fire extinguishingsystem is commissioned and—preferably—equally also within a period ofuse of a year and quite particularly preferably also within a period ofuse of five years after commissioning of the fire extinguishing system.

In principle pipes comprising centrifugal concrete, cement-clad castiron, high-quality steel, copper and reinforced glass fiber are alsosuitable at least to a limited extent for ensuring a value in theclaimed ranges for the constant C, but for different reasons they areruled out in terms of their surface-coverage use entirely: pipes ofcentrifugal concrete or cement-clad cast iron have a wall which is muchtoo thick and related thereto a weight which is much too great so thattheir surface-coverage in the sense of a usual use in buildings isalready impossible for that reason alone. For the above-mentionedreasons of weight and by virtue of their excessively low flexural indexpipes of centrifugal concrete or cement-clad cast iron can be consideredexclusively in the ground as transport means (3) for connecting themeans (1) for providing the extinguishing medium to the at least onemeans (2) for applying the extinguishing medium; pipes of high-qualitysteel, copper and reinforced glass fiber are admittedly possible inprinciple, but they are much too high in price and that has not gainedacceptance in the market. In addition pipes of reinforced glass fiberand generally plastic are combustible or melt at high temperatures,which limits their use to regions involving a low burning loading and/orto being laid within cast concrete slabs. All three types of pipe whichare possible in principle are not suitable for solving the underlyingproblem of the invention.

The invention is practically not limited in respect of the nominal sizefor the transport means (3) for connecting the means (1) for providingthe extinguishing medium to the at least one means (2) for applicationof the extinguishing medium, in particular and preferably the mild steelmetal pipes for providing the transport means (3) should be of a nominalwidth in a range of DN 32 to DN 250, which corresponds to the commonpipe nominal widths of the main conduit [(3), a], for example in theform of riser conduits, of the fire extinguishing system proposed here,by way of possible secondary distribution pipes [(3),b], for example inthe form of distributor conduits, as far as the sprinkler connectionpipes [(3),c], for example in the form of branches (branch conduits). Ina quite particularly preferred configuration the mild steel metal pipesfor providing the transport means (3) are to be of a nominal width in arange of DN 32 to DN 65, which corresponds to the pipe nominal widths ofusual secondary distribution pipes to the sprinkler connection pipes.

Without being restricted in this respect in accordance with the presentinvention the following examples for the means (2) for application ofthe extinguishing medium are deemed to be particularly preferred:sprinklers, in particular in the many configurations forming part of thestate of the art, nozzles, simple pipe openings, and comparablecomponents and devices for the issue and distribution of theextinguishing medium.

The fire extinguishing system proposed here is intended for the use ofextinguishing media, wherein the medium is preferably chosen from thelist including: water, foam, water-foam mixture, gas and chemicalextinguishing agents.

In particular CO₂ and the noble gas argon are suitable for theextinguishing medium gas, while for the chemical extinguishing agents inparticular those as are known at the date of filing of thisspecification are selected from:—the trade name FM-200® from DuPont ofGeneva, Switzerland, and the trade name Novec™ 1230 from 3M of Neuss,Germany.

In particular the following: water film-forming foaming agent, forexample ‘Extensid AFFF 1%-3%‘ from’Fabrik chemische Präparate RichardSthamer GmbH & Co KG’ of Hamburg, Germany, and also ‘Fomtec AFFF’ from‘Rosenbauer International AG’ of Leonding, Austria, alcohol-resistantfoaming agent, for example ‘Extensid AFS LV 1%-3%’ from ‘Fabrikchemische Präparate Richard Sthamer GmbH & Co KG’ of Hamburg, Germany,and also ‘Fomtec ARC’ from ‘Rosenbauer International AG’ of Leonding,Austria, protein foaming agent, for example ‘Promax Spezial’ from‘Minimax GmbH & Co KG’ of Bad Oldesloe, Germany are deemed to bepreferred as the foam, in the water-foam mixtures those types of foamare used in conjunction with water, wherein a ratio related to % byvolume:

-   -   water:foam

in a range of 100:1 to 100:3 is deemed to be particularly preferred.

A suitable frost protection agent can be added to the extinguishingmedium, selected from the list including: water and water-foam mixture,to avoid splitting or blowout and/or damage of the means (2) forapplying the extinguishing medium, and in particular the transport means(3) for connecting the means (1) for providing the extinguishing mediumto the at least one means (2) for applying the extinguishing medium atlow temperatures of use, preferably in a temperature range of 0 to −25°C., quite particularly preferably in a temperature range of 0 to −28° C.In particular the following are deemed to be preferred as frostprotection agents: glycol-based frost protection agents, polypropyleneglycol-based frost protection agents, and calcium chloride-based frostprotection agents.

If water or a water-foam mixture is used as the extinguishing mediumthen preferably a single water supply presents itself for providing thatextinguishing medium, and when the situation involves demands of higherreliability even a double water supply. The single or double watersupply can be replaced or quite particularly preferably supplemented byat least one storage component for the extinguishing medium, selectedfrom the list including: an open reservoir, a high-level tank,intermediate and supply containers. In that respect preferably the atleast one storage component selected from the list including: high-leveltanks and intermediate and supply containers, preferably has an inwardlydisposed corrosion protection coating quite particularly preferablyconsisting of concrete and/or plastic.

The fire extinguishing system proposed here for distributing anextinguishing medium in all embodiments and variants disclosed hereincan be both in the form of a wet sprinkler installation in which thetransport means (3) is permanently filled with a or with theextinguishing medium, or also equally in the form of a dry sprinklerinstallation in which the transport means (3) are usually filled with agas and the extinguishing medium is transported therethrough only in thesituation of use. Both the above configurations of the fireextinguishing system proposed here are deemed to be preferred inaccordance with the present invention.

In principle many different coatings for the transport means (3) areconceivable, like, for example, anodic and also cathodic dip-paintcoating and Parkerising, with which the feature that is essential to theinvention ‘for ensuring a value for C in a range of 125 to 150 when thefire extinguishing system is commissioned’ can be fulfilled. After manyintensive considerations and tests linked to those considerations aparticularly preferred configuration of the present invention of a novelfire extinguishing system is implemented if the inwardly disposedcorrosion protection coating of the transport means (3) which are atleast partly in the form of mild steel metal pipe is afforded by theAquence™ method, in particular by means of the Aquence™ method of the900 series.

The Aquence™ method developed by Henkel of Düsseldorf, Germany forms acoating here at the inside of the transport means (3) which are in theform of metal pipes, on a chemical basis, in which FeF₃ iron fluoridewhich is supplied in the form of a solution in fundamental fashion andwith a view to the invention presented here provides for a liberation ofFe²⁺ ions at the inside surface of the metal pipes, which bond to paintparticles which are equally supplied in the form of the foregoingsolution and which are then again deposited at the inside surface of themetal pipes. In the course of a prolonged deposition process over aperiod of a preferred length of 4 to 8 minutes, quite particularlypreferably over a period of a length of 5 to 7 minutes, a coating isbuilt up in that way, of a layer thickness in a preferred range of 15 to28 μm, quite particularly preferably in a range of 21 to 27 μm. With theparticularly preferred Aquence™ method of the 900 series anepoxy/acrylic-based inwardly disposed corrosion protection coating isproduced in the above-described manner.

The inwardly disposed corrosion protection coating which is quiteparticularly preferably constituted by a continuous through flow withthe solution in particular in accordance with the Aquence™ method of the900 series ensures to a particularly persuasive degree that a value forC is guaranteed in a range of 125 to 150 when the fire extinguishingsystem is commissioned and even in a range of 135 to 150 within a periodof use of 5 years. A further substantial advantage of anepoxy/acrylic-based inwardly disposed corrosion protection coatingformed in that way is its resistance to: the preferred extinguishingmedia selected from the list including: water, foam, water-foam mixture,gas and chemical extinguishing agents, and the extinguishing agentadditives, in which respect in particular the preferred frost protectionagents are meant here.

In the numerous tests that preceded this invention it was found that, tobuild up a sufficiently thick epoxy/acrylic-based Aquence™ coating acontinuous flow through the mild steel metal pipes (3) with the solutionin accordance with the Aquence™ method of the 900 series using athrough-flow speed within a range of 9 m/min to 18 m/min and even better12 m/min to 15 m/min over a period of a preferred length of 4 to 8minutes and quite particularly preferably over a period of a length of 5to 7 minutes is to be ensured, for which reason the specified ranges forthe through-flow speed are deemed to be preferred solely and preciselyin combination with the through-flow time.

By virtue of the fact that the inwardly disposed corrosion protectioncoating in accordance with all embodiments proposed here ensures a valuefor C at least in a range of 125 to 150 the inside of the metal pipes(3) is distinguished by a completely even and non-porous sealing meanswhich even over many years can no longer have the extinguishing mediumwhich is passed through the metal pipes (3) infiltrating therebeneath,for which reason such mild steel metal pipes for providing the transportmeans (3) can be of a wall thickness which is quite particularlypreferably in a range of only still 2.0 mm to 2.5 mm, instead of the 2.6mm thickness which today is still usual: thicker walls for the transportmeans (3) for connecting the means (1) for providing the extinguishingmedium to the at least one means (2) for applying the extinguishingmedium are no longer necessary for ensuring the greatest possible levelof availability certainty. With the metal pipes (3) remaining of thesame outside diameters the inside diameter can thus be increased by 0.2mm to 1.2 mm.

In applying the invention proposed here in all the embodiments proposedhere the through-flow rate Q through the pipes, in the form of a mildsteel metal pipe with an inwardly disposed corrosion protection coatingcharacterizing the invention can be increased by a percentage in a rangeof 4% to 34%, related to the through-flow rate of galvanized pipes.

DRAWINGS

The FIGURE hereinafter is intended to describe the invention more fully.

The FIGURE shows the structure in principle of an installationimplemented for test purposes and to verify the invention made, that isin the form of a dry sprinkler installation with periodicallyimplemented sprinkler inserts.

DETAILED DESCRIPTION

A branched system of transport means (3) is connected to a means (1)(only diagrammatically indicated) for providing the extinguishingmedium, here water, in the form of a single water supply, wherein thetransport means (3) include a central riser conduit [(3), a] a pluralityof distributor conduits [(3), b] branching from the central riserconduit [(3), a], and for each distributor conduit [(3), b] a respectiveplurality of branches or branch conduits [(3), c]. In that respect forthe sake of simplicity of the drawing, the FIGURE completely shows onlyone distributor conduit [(3), b] and in relation thereto only a fewbranches [(3), c].

Each branch [(3), c] has at its beginning directed to the distributorconduit [(3), b] and at its end a respective ball valve (5), upstream ofthe ball valve (5) at the end of the branch [(3), c] a manometer (6),three respective sprinklers as means (2) for applying the extinguishingmedium, and a plurality of coupling connections (4) for possibleindividual replacement of each sprinkler (2).

In total fitted in the test installation there are thus a total of 60branches [(3), c] of a respective nominal width of DM 32 and of arespective wall thickness of 2.6 mm, five branches [(3), c] of mildsteel metal pipes with an epoxy/acrylic-based inwardly disposedcorrosion protection coating. In that arrangement that inwardly disposedcorrosion protection coating in all of those five branches [(3), c] isof a thickness in a range of 15 to 27 μm, in the branches [(3), c] ofthe particularly preferred variant the thickness is in a narrower rangeof 21 to 27 μm. In all of those five branches [(3), c] theepoxy/acrylic-based inwardly disposed corrosion protection coating isproduced by means of the Aquence™ method of the 900 series. A further 49branches [(3), c] of the test installation are constructed withgalvanized mild steel metal pipes, the remaining six branches [(3), c]have mild steel metal pipes without any internal coating.

After a 12 month test time with constantly changing operating conditionsand severe outside climate fluctuations from moist-warm through dry-hotto dry-cold and wet-cold the branches [(3), c] of mild steel metal pipeswith the epoxy/acrylic-based inwardly disposed corrosion protectioncoating exhibit scarcely any corrosion at the respective branch endswhile surface corrosion cannot be detected at all. All threads on therespective coupling connections (4) after the end of the test time arealso still completely sealed and exhibit in principle no corrosionattacks. In contrast both the galvanized mild steel metal pipes and alsothe mild steel metal pipes without any internal coating at the branchends and towards the coupling connections (4) have a marked rustingattack in the pipe interior, even if slight but clearly detectable,which leads to a marked reduction in the C-values. Only the mild steelmetal pipes with the epoxy/acrylic-based inwardly disposed corrosioncoating have a value for C of 140 at the end of the 12-month testperiod, which exactly corresponds to the value at the beginning of thelong-term test.

Thus the realizations deriving from operation of the test installationshow on the one hand the great advantages of a fire extinguishing systemaccording to the invention over previous fire extinguishing systems,while on the other hand they also show that, by means of the fireextinguishing system according to the invention, the underlying problemsof the invention for achieving a monetary improvement in the design andoperation of sprinkler installations can be lastingly solved.

LIST OF REFERENCES

-   -   (1) means for providing the extinguishing medium    -   (2) means for applying the extinguishing medium    -   (3 transport means    -   (3), a—riser conduit    -   (3), b—distributor conduit    -   (3), c—branch (conduit)    -   (4) coupling connection    -   (5) ball valve    -   (6) manometer

What is claimed is:
 1. A fire extinguishing system for distributing anextinguishing medium, at least comprising: means for providing theextinguishing medium, at least one means for applying the extinguishingmedium, transport means for connecting the means for providing theextinguishing medium to the at least one means for applying theextinguishing medium, wherein the transport means are at least partiallyin the form of a plurality of mild steel metal pipes connected togetherby a plurality of coupling connections, wherein the pipe friction lossin each of the plurality of mild steel metal pipes is defined inaccordance with the Hazen: Williams formula withP=6.05·10⁵ ·L·Q ^(1.85) ·C ^((−1.85)) ·d ^((−4.87)) wherein: P=pressuredrop in each of the plurality of mild steel metal pipes, in bars,Q=through-flow rate through each of the plurality of mild steel metalpipes, in l/min, d=mean inside diameter of each of the plurality of mildsteel metal pipes, in mm, C=constant for type and condition of each ofthe plurality of mild steel metal pipes, and L=equivalent length of eachof the plurality of mild steel metal pipes and shaped portions, in m,wherein: each of the plurality of mild steel metal pipes has an at leastinwardly disposed corrosion protection coating, the inwardly disposedcoating comprises a non-porous polymer layer containing iron andepoxy-acrylic, the non-porous layer being ionically bonded to at leastan inner surface of each of the plurality of mild steel metal pipes andhaving a thickness greater than 15 μm to provide a value for C in arange greater than 120 to 150 when the fire extinguishing system iscommissioned for use; and wherein each of the plurality of mild steelmetal pipes has a nominal width in a range of DN 32 to DN
 250. 2. A fireextinguishing system according to claim 1, wherein the non-porouspolymer layer provides a value for C in a range of 125 to
 150. 3. A fireextinguishing system according to claim 1, wherein non-porous polymerlayer provides a value for C in a range of 135 to
 150. 4. A fireextinguishing system according to claim 1, wherein the non-porouspolymer layer provides a value for C in a range of 135 to 150, andwherein the thickness greater than 15 μm comprises a thickness in therange of 15-28 μm.
 5. A fire extinguishing system according to claim 1,wherein each of the plurality of mild steel metal pipes for forming thetransport means has a nominal width in a range of DN 32 to DN
 65. 6. Afire extinguishing system according to claim 2, wherein each of theplurality of mild steel metal pipes for forming the transport means hasa nominal width in a range of DN 32 to DN
 65. 7. A fire extinguishingsystem according to claim 5, wherein each of the plurality of mild steelmetal pipes for forming the transport means has a wall thickness in arange of 2.0 mm to 2.5 mm.
 8. A fire extinguishing system according toclaim 1, wherein the extinguishing medium is a medium selected from thelist including: water, foam, water-foam mixture, gas, and chemicalextinguishing agents.
 9. A fire extinguishing system according to claim1, wherein the means for providing the extinguishing medium include atleast one storage component for the extinguishing medium, wherein the atleast one storage component is selected from the list including: openreservoir, a tank and supply container.
 10. A fire extinguishing systemaccording to claim 9, wherein the at least one storage componentselected from the list including: the tank and supply container, has aninwardly disposed corrosion protection coating of concrete and/orplastic.
 11. A fire extinguishing system according to claim 1, whereinthe means for providing the extinguishing medium, selected from the listincluding: water and water-foam mixture, is from a single water supply.12. A fire extinguishing system according to claim 1, wherein the meansfor providing the extinguishing medium, selected from the listincluding: water and water-foam mixture, is from a double water supply.13. A fire extinguishing system according to claim 1, wherein frostprotection agent is added to the extinguishing medium selected from thelist including: water and water-foam mixture.
 14. A fire extinguishingsystem according to claim 1, wherein the plurality of couplingconnections comprises a plurality of threaded coupling connections, eachof the plurality of threaded coupling connections having sealed threads.15. A fire extinguishing system for distributing an extinguishingmedium, the system comprising a plurality of corrosion resistant pipes,each of the plurality of corrosion resistant pipes comprising a mildsteel pipe with a non-porous layer ionically bonded to at least aninterior surface of the mild steel pipe, the non-porous layer containingiron and epoxy-acrylic, and having a thickness of at least 15 μm toprovide a C value in a range greater than 120 to 150; and wherein eachmild steel pipe has a nominal width in a range of DN 32 to DN
 250. 16.The fire extinguishing system for distributing an extinguishing mediumof claim 15, wherein the mild steel pipe comprises a nominal width in arange of DN 32 to DN
 65. 17. The fire extinguishing system fordistributing an extinguishing medium of claim 16, wherein the mild steelpipe comprises a wall thickness in a range of 2.0 mm to 2.5 mm.
 18. Thefire extinguishing system for distributing an extinguishing medium ofclaim 15, wherein the non-porous layer containing iron and epoxy-acrylicis ionically bonded to an exterior surface of the mild steel pipe. 19.The fire extinguishing system for distributing an extinguishing mediumof claim 18, wherein the thickness of the non-porous layer of at least15 μm comprises a thickness in the range of 21-27 μm.
 20. A method ofproviding a fire extinguishing system for distributing an extinguishingmedium, the method comprising: obtaining a plurality of corrosionresistant pipes, each of the plurality of corrosion resistant pipescomprising a mild steel pipe with a non-porous layer ionically bonded toat least an interior surface of the mild steel pipe, the non-porouslayer containing iron and epoxy-acrylic, and having a thickness of atleast 15 μm to provide a C value in a range greater than 120 to 150;wherein the mild steel pipe comprises a nominal width in a range of DN32 to DN 250; and providing the plurality of corrosion resistant pipeshaving a C value in the range greater than 120 to 150 for use as atransport means in a fire extinguishing system.
 21. The method ofproviding a fire extinguishing system for distributing an extinguishingmedium of claim 20, wherein the mild steel pipe comprises a nominalwidth in a range of DN 32 to DN
 65. 22. The method of providing a fireextinguishing system for distributing an extinguishing medium of claim21, wherein the mild steel pipe comprises a wall thickness in a range of2.0 mm to 2.5 mm.
 23. The method of providing a fire extinguishingsystem for distributing an extinguishing medium of claim 20, thenon-porous layer containing iron and epoxy-acrylic is ionically bondedto an exterior surface of the mild steel pipe.
 24. The method ofproviding a fire extinguishing system for distributing an extinguishingmedium of claim 20, wherein the thickness of the non-porous layer of atleast 15 μm comprises a thickness in a range of 21-27 μm.
 25. The methodof providing a fire extinguishing system for distributing anextinguishing medium of claim 20, wherein the plurality of corrosionresistant pipes comprises at least a plurality of distributor conduitsand a plurality of branch conduits.
 26. The method of providing a fireextinguishing system for distributing an extinguishing medium of claim20, further comprising: providing a plurality of coupling connectionsfor the plurality of corrosion resistant pipes, the plurality ofcoupling connections having sealed threads.